甲 Jiǎ — the Yang Wood Day Master

What the classics read it as

Yang Wood. The image the classics reach for is not a plant but a beam — 甲 is the tree that is going to be timber, growing straight because straight is the only direction it has.

《滴天髓》 opens its account of the ten stems here: 「甲木參天，脫胎要火」. Jia wood reaches into the sky, and to be delivered out of the seed it needs fire. The second clause is the one readers skip. A tree that only grows is not finished. Fire in this reading means output — the thing made from the wood — and without it 甲 is a large healthy trunk that was never cut into anything.

What it loves: fire, to bring it out. Water at the root, in the quantity rain arrives in rather than flood. Ground solid enough to hold against, since a tree pushes down before it pushes up.

What it fears: 「春不容金，秋不容土」 — in spring it will not tolerate metal, in autumn it will not tolerate earth. Spring wood is a sapling and metal is the axe; the cut that shapes a mature tree kills a young one. Autumn wood has already given its harvest, and more ground piled on at that point is only weight.

The character that follows from the image is not adaptable. This is the Day Master the tradition associates with going straight at things, with holding a position past the point where holding it stays comfortable, and with a slowness that reads as obstinacy from outside and as certainty from inside.

The cost, said plainly: a tree cannot move. Whatever ground you were planted in is the ground you grow in, and of the ten stems this is the one least able to solve a problem by leaving it.